NUTS AND VOLTS

Posted in: Nuts and Volts

ACKme Networks appoints Lemos International Company Inc.

January 2015

Lemos International Co., Inc., of Barrington, RI and Merritt Island, FL has been appointed by ACKme Networks of Los Gatos, CA as its North American distributor and Value Added re-seller. ACKme offers fully certified small form factor Wi-Fi, Low Energy Bluetooth modules, and GSM Gateway solutions optimized for cellular sensor or command / Control applications. 

 


Lemos has been a distributor for the high-end electronics industry since 1996, offering state-of-the-art technology. In 2011, Lemos International opened a facility in Merritt Island in order to better serve its customers as they design RF solutions for their products.   Lemos commented that ACKme will fit perfectly into its current portfolio of high-end wireless products.


Posted on 01/15 at 11:19 am
Posted in: Nuts and Volts

An Intro and Antennas

January 2015 H. Ward Silver

Welcome to the world of wireless know-how in the form of amateur or "ham" radio. Where else can you be an electronics and programming whiz, study solar and atmospheric phenomena, design your own communication system, and provide valuable public service — all at the same time? Amateur radio and the Nuts & Volts readership have a lot in common. Let's get to know each other!


I’m thrilled to help return ham radio to the pages of Nuts & Volts! In every other issue, I’ll be discussing some aspect of ham radio technology that you can use on your workbench and in your projects — whether you have (or get!) a license or not. Over the years, NV has featured ham radio in articles and columns so ham radio was never truly absent. The magazine’s editor is a ham (NU1N) and Paul Verhage — maven of the high altitudes and Near Space columnist — is also known as KD4STH. Many of the authors hold an amateur “ticket,” so maybe they will share their call signs with us in future articles. You may be surprised at how widespread amateur radio really is!

A little about my background: I have a degree in Electrical Engineering and spent 20 years in various types of industrial and medical product development — both hardware and software. I’ve had an amateur radio license since my high school days and am now known on the ham bands as NØAX (the slash is silent). For the last dozen years or so, I’ve been writing and editing books and columns for the American Radio Relay League (www.arrl.org), such as the three licensing study guides; a classic reference for radio technology, The ARRL Handbook; and a nearclassic antenna reference, The ARRL Antenna Book.

Some of my other books and columns are included in the sidebar on resources, including Ham Radio for Dummies. I’m pretty active on the air and like to operate in competitive events known as radiosport, as well as provide public service and study radio wave propagation. There is more on my “ham radio bucket list” than I will ever get to!

So, what is this ham radio stuff anyway and why should you care? First, there is far, far more to amateur radio in the 21st century than in the movies. Those images you see of glowing tubes and racks full of black crinkle-finish equipment with the jumping meters and dials? They are as obsolete as 8” singlesided floppy disk drives and 7400 family TTL logic! Sure, some of that gear is still out there on the air, but today’s ham radio is up to date and innovative.

Hams are big players in the Arduino and Raspberry Pi communities, just as they are in developing over-the-air digital communications protocols and networks. Even if you’re not really interested in the full ham radio experience, you might be interested in using non-licensed wireless data links in your projects, for example. Whatever your specialty, learning about radio will help you select, apply, and use wireless technologies better.

Modern-day ham radio is really a combination of three important components. The first is science: Hams learn about radio circuits and systems, antennas, how signals propagate from place to place, and the antennas that make it happen. The second is skill: By practicing effective operating, hams apply that science to insure that signals get from point A to point B. Finally, the ham combines the science and skill in service of his or her fellow citizens. You may have seen the motto “When All Else Fails,” which refers to the ham’s storied ability to fill in when commercial and government communications are disrupted.

All three aspects — science, skill, and service — are important, and there is a home for you in whichever area is most interesting.

This column will touch a lot of bases: antennas, transmission lines, batteries, digital protocols, radio frequency (RF) circuits and techniques, test equipment, and the list goes on. We’ll discover that components act a lot differently above a few megahertz (MHz) than they do at audio and DC. I will show you how to install those pesky feed line connectors so the signal goes to the right place.

Similarly, we’ll take a look at ways to keep RF signals from leaking out of and getting into your equipment. In some columns (like the one this month), there will be an experiment or activity you can do to gain valuable experience and maybe even a useful gadget. Ready to get started? I thought so!

The Ground Plane Antenna

There is no subject better suited to kick off a column about ham radio technology than antennas. All forms and specialties of ham radio share antennas as a common part of the station. If it’s ham radio, you can be sure of an antenna being involved. Actually, a lot of non-amateur electronics also deal with antennas, such as wireless links and mobile phones.

 

Figure 1. Basic ground plane construction showing the formula for the length of the vertical element and radials.At least two radials are required; four are recommended, and should be arranged symmetrically around the vertical element.

Figure 2. The quarter-wavelength long ground plane antenna behaves similarly to a half-wavelength long dipole antenna with two quarter wavelength halves. It uses a solid conductive sheet or radial wires to supply the same effect as that of the “missing” quarter-wavelength. In this column, I’ll introduce you to one of the simplest antennas and show you how to make one to use at home — or even design your own.

Figure 1 shows the basic idea: A vertical wire is attached to the center conductor of a coaxial cable connector, and several radial wires are attached to the mounting holes of the connector. This particular style of connector is called a receptacle or panel jack because it is designed to mount on a panel and have a cable attached to it. (Bulkhead receptacles mount with a nut and lock washer in a single hole, and won’t work for this particular antenna.)

A family of connectors shares common attachment mechanisms and body sizes. The receptacle we’re using here is from the BNC family. (Other common connector families include SMA, N, and UHF.)

The vertical wire — called an element — is the main part of the antenna that receives the signal. Does the orientation of the element matter? Yes, it does. Radio waves are made up of an electric or E field and a magnetic or H field that are at right angles to each other.

The magnetic field makes electrons move in tight little circles which is not very useful in creating currents that flow to a receiver. The electric field, however, makes electrons move in a straight line. In this case, the antenna is designed so the E field will make the electrons move back and forth along the wire element, into the coaxial cable, and down the cable to the receiver.

The orientation of the electric field determines the radio wave’s polarization — horizontal or vertical.

When the antenna element and radio wave E field are aligned, the antenna receives the strongest signal. The orientation of the antenna’s element or elements determines the antenna’s polarization. In this case, the antenna is vertically polarized. Since the NOAA Weather Station broadcasts that this antenna is designed to receive are transmitted by a vertically polarized antenna, our antenna should be vertically polarized to receive the maximum signal. (Misalignment is called crosspolarization and can result in up to 99% or 20 decibels [dB] of signal loss because the E field no longer makes electrons move along the antenna element as receivable current.)

An Electrical Mirror

The name “ground plane” comes from the four radial wires — so-called because they extend radially from the center. The ground plane acts as an electrical mirror to create an electrical image of the antenna’s missing half. Missing half? Yes, the ground plane antenna is actually one-half of a dipole as shown in Figure 2.

The mirroring effect of the ground plane is the same as that of the missing part of the dipole. In this case, four radials are enough to do the job. For ground plane antennas mounted on vehicles, the radials are replaced by the sheet metal of a roof or trunk.

A one-half wavelength long dipole is an effective antenna that radiates and receives equally well in all directions around the antenna’s axis. If the dipole is vertical, the equal response from any direction makes it omnidirectional.

That omnidirectional response is not repeated if one looks at the antenna’s response from the side. Figure 3A shows the ground plane’s elevation pattern starting at the horizon (0°) on one side, going over the top of the antenna (90°), and back to the opposite horizon. The antenna receives very little signal overhead because the E field of a radio wave coming from that direction only moves an electron back and forth across the element, not along the element where it becomes a current that can be received.

Figure 3A. These are radiation patterns showing how strongly an antenna responds to signals arriving from various directions.The distance from the center to the solid line shows the strength of the response in decibels with respect to the maximum response.This figure shows an elevation pattern looking at the antenna from the side. Figure 3B. The threedimensional pattern resembling a bagel with the antenna at the center.The patterns were generated by the EZNEC antenna modeling software (www.eznec.com).

 

The notch in the antenna’s pattern is called a null, whereas the region of maximum response at the horizon is a lobe. An azimuth pattern would look down on the antenna from the top and show how well the antenna receives in all directions or azimuths. Since the antenna is omnidirectional, that pattern would be a simple circle.

Figure 3B shows what the antenna’s three-dimensional response looks like — sort of a bagel shape if the antenna was stuck through the middle.

By replacing the lower half of the dipole with its image, the quarterwave ground plane achieves the same effect of a vertical dipole, but in a smaller package with easier mounting. Ground plane antennas are common at frequencies from the AM and long-wave broadcast bands (at and below 1.7 MHz), all the way up to about 1 GHz wherever an omnidirectional response is desired.

A Ground Plane Antenna for NOAA Weather Stations

Many scanners and VHF radios have the ability to receive the seven NOAA weather station channels near 162.5 MHz (www.nws.noaa.gov/os/marine/wxradio.htm). The flexible whip (also known as “rubber duck”) antennas provided with portable radios are not very efficient. If you are in an area of weak coverage or are traveling to a remote area, you may need a full size antenna to pull in these stations. By building this simple ground plane antenna, you will be able to receive more of the stations over a wider area.

Parts List and Instructions

• Six foot BNC-to-BNC coaxial cable (RG-58 or RG-8X cable)
• BNC panel jack (UG-290 style or any flange-mount style)
• Eight feet of #14 AWG solid copper wire or brass rod (#12 to #16 will work and stand up to handling)
• Four ring crimp terminals for 12-16ga wire (blue insulation) for #4 stud
• #4 hardware to attach terminals to connector flange

Start by calculating the length of wire for the vertical element and the four radials. All five will be the same length. Use this equation with a frequency of 162.5 MHz:

L (inches) = 2772 / f (MHz) = 2772 / 162.5 = 17.1 inches 

Where does the equation come from? Remember that the ground plane’s vertical element is one-quarter wavelength long or λ/4, where the Greek letter λ stands for wavelength. In free space at the speed of light, λ = 300 x 108 m/sec / frequency or λ/4 = 75 / frequency in MHz. Converting to inches, λ = 2798 / f (MHz). So, why are we using 2772 instead of 2798?

Figure 4. Close-up of the assembled ground plane showing one method of attaching radial wires to the BNC connector flange. Radials may be attached permanently by soldering, or temporarily with screws.


The speed at which a radio wave travels along a piece of wire is slower than in air or the vacuum of free space. That makes the wire act electrically longer than its physical length. In other words, λ/4 is shorter when the wave is traveling on a wire than it is when the wave is traveling in free space. The thicker the wire, the slower the wave travels. This is called the length-to-diameter (l/d) effect and it must be accounted for when determining the length of antenna elements. For #14 wire, the l/d effect results in the use of 2772 instead of the free space value of 2798.

Cut five pieces of wire. Crimp a terminal onto one end of four of the pieces. Solder the remaining piece of wire to the BNC receptacle’s center pin. Attach each radial to the receptacle with the #4 hardware.

Figure 4 shows one way to do it. Bend the radials down (away from the vertical element) about 45 degrees and arrange them symmetrically around the receptacle. Attach the coaxial cable to the antenna and the radio – you’re done! Figure 4 is a close-up of the antenna’s feed point where the feed line is attached. (If your radio uses some other type of

connector than BNC, you’ll need to use an adapter.) If your radio has a signal strength meter, compare your new antenna to the flexible antenna provided with your radio. Why are the radial wires bent at an angle when Figure 2 shows the ground plane as flat? If the radial wires (or conductive sheet) are at right angles to the vertical element, the feed point impedance of the ground plane will be about 35W which is different than that of the coaxial cable (which is usually 50W). This mismatch will make it harder for signals in the vertical element to transfer to the coax, and reduces the effectiveness of the antenna a bit. 

By bending the radial wires down, the feed point impedance is raised closer to 50W. (Cable impedance will be the subject of a future column.)

Your antenna will perform well over a fairly wide range of frequencies that are up to ±5% from the design frequency. Table 1 shows the wire length for several commonly monitored radio services. Assuming you don’t want to hold the antenna up in the air with one hand when you want to use it, you can simply tape the supporting cable to a piece of dowel, pipe, conduit, or whatever is handy. Secure the support so the antenna is in the clear and at least l/2 away from any other metal surface or object.
 


I hope you’ve enjoyed this first installment of The Ham’s Wireless Workbench and will be a regular reader as we explore the world of ham radio technology. Visit the ARRL website and read what’s there — you’ll learn a lot and maybe I’ll eventually hear you on the air with your own call sign!

Until then, 73!
(That’s the ham’s shorthand for “best regards.”) NV
 

Radio and Radiation
The word “radiation” tends to get people excited because the same word is used to apply to all types of radiated energy — from radio waves to infrared light to X-rays and atomic particles. Radio waves as we are discussing here are non-ionizing, meaning they do not have enough energy to knock electrons away from atoms creating ions. The only effect from radio waves on humans is thermal or heating. For radiation to become ionizing, it takes extreme ultra-violet, X-rays, gamma rays, or particles to create ions and cause chemical changes in cells. For more information on safety issues associated with radio waves or RF, see http://www.arrl.org/rf-radiation-and-electromagnetic-field-safety

 

Where Does the Term “Ham” Come From?
Everybody wants to know why it’s called “ham” radio. While there are many answers floating around, the truth is that no one really has the definitive answer. Nevertheless, after being asked thousands of times, the most common and reasonable source of “ham” is that it was originally a not-very-complimentary term used to refer to the amateurs by commercial and military operators. In those days of spark transmission — the original ultra-wideband signal! — everybody had to share all of the radio spectrum, so interference was a huge problem. The amateurs turned the term into a badge of pride that persists to the present day. It’s not an abbreviation for anything, so it’s never capitalized. It’s referring to the original hackers — the hams.

 

Your Go-To Source for Radio Know-How – the ARRL

 

 

 

 

     The world’s oldest amateur radio organization is also the United States’ national amateur radio institution: the American Radio Relay League, or the ARRL (http://www.arrl.org). Usually referred to by hams as “the League,” the ARRL’s motto is “Of, By, and For the Amateur.” It represents amateur radio internationally and in Washington, D.C. to insure that hams have the necessary spectrum to fulfill the amateur service’s role.
     Within the amateur radio community — more than 700,000 in the United States alone — the ARRL’s role is to educate amateurs, support the volunteers who perform all licensing activities, and provide training and service activities to keep the skills of hams sharp and ready.
    The ARRL publishes an enormous amount of technical and operating material in whatever area of amateur radio is most attractive to you. If you would like to explore some of the technology resources on the ARRL website, there is a special portal just for you at www.arrl.org/tech-portal.

 

Ham Radio for Dummies, Second Edition (Ward Silver NØAX) — An introduction to ham radio that explains what it is and how it works in bite-sized chunks. 

 

Ham Radio License Manual (ARRL) and Technician Class FCC License Prep (Gordon West) – The ARRL and other organizations publish study guides for all three exam licensing levels. Online study resources like http://www.hamradiolicenseexam.com/ and http://www.kb6nu.com/tech-manual-feedback/ are also available to help you pass the tests.

 

ARRL Handbook — Now in its 92nd edition, “the Handbook” covers nearly all areas of amateur radio technology from tutorials in basic electronics to the latest digital protocols and equipment innovations. See the ARRL Store (http://www.arrl.org/shop/technical) for a long list of technical books.

College students and educators will want to bookmark the web portal that supports university level ham radio interests at http://www.arrl.org/college-students-and-educators.


Posted on 01/15 at 9:42 am
Posted in: Developing Perspectives

Just in Time Parts vs. the Junkbox

January 2015 Bryan Bergeron

Cleaning out my workshop reminded me of when I first started my journey in electronics — tubes were still available at RadioShack. My first ham radio transmitter — a HeathKit DX-60B — used a 6146B tube final amplifier (power amplifier), in part because it was inexpensive and readily available. Back then, I had a junkbox with a few dozen tubes, a pound or two of discrete resistors and capacitors, and some miscellaneous hardware. With that, I could repair just about any TV, receiver, or transmitter that I came across or wanted to modify.


Today, things are more complicated, in part because of the vast array of specialized solid-state components and assemblies available. Moreover, the shelf life of these components and assemblies are typically months instead of years or decades.

Don't get me wrong. I look forward to getting my hands on the latest developments in technology. I'm hooked, for example, on the new product announcements featured by SparkFun every Friday, and the broader daily updates on technology from Gizmodo. It's just that it no longer pays to have a sizeable junkbox.

For example, about a year ago, I created a prototype circuit for a government grant application that relied on some high-resolution TFT LCD modules from AdaFruit. However, in the nine months between the grant application and funding, the TFT LCD had been discontinued. As a result, I had to experiment with a new crop of LCDs and newly introduced OLEDs from AdaFruit. I was happy with the new displays, which provided higher resolution, faster response, and no increase in price. However, I had to modify the 3D printer file for the mounting assembly, and rework the software to accommodate the new generation of displays.

Today, after clearing out perhaps 20 lbs of retired ASICs (applicationspecific integrated circuits), breakout boards, and circuit assemblies, my junkbox consists largely of leaded and SMT resistors, capacitors, and a few 3V and 5V power regulator chips. I've downsized from six shelves of "junk" to one shelf of discrete components. 

As a result, there's less to keep track of, and I know where everything is. Previously, it was a hunt to find that elusive chip or breakout board. Now, my hunting is reserved to online searches.

The two to three day time lag is a significant downside, but no greater than working with components that are no longer supported. So far, this “just in time” parts procurement has worked just fine.

As an aside, I've also shifted from what I once considered standard 4-40 stainless nuts and bolts from suppliers such as BoltDepot, to lighter smaller M2x10 hardware from places such as HobbyKing. I wouldn't think of building a drone or any other compact lightweight device with the old hardware. 

However, there's still enough of the heavy duty boards around such as the Arduino UNO microcontroller board to hang on to my supply of 4-40 hardware. I'm sure that eventually — as with my collection of RF vacuum tubes — I'll be tossing these, as well. NV


Posted on 12/14 at 1:01 pm
Posted in: Featured Article

Save Time and Money Making CNC Halloween Decorations

November 2014 Len Shelton Melissa Shelton

When my friend,Vern asked me if I'd write an article for Nuts & Volts demonstrating how to create a Halloween decoration tombstone on a CNC router, I was psyched. I’m always looking for new and interesting ways to show off all you can do with CNC machines. So, I agreed to give it a shot.


Create complex 3D contoured parts by combining fast and simple 2.5D pocketing and profiling operations with manual finishing techniques.

Getting Started

As with any project, you have to do your research. I needed to answer questions like: What do tombstones look like? How are they shaped? What do they say on them? How are people using them in their Halloween displays? Most importantly: How do I make them on a CNC router? So, I got a lot of great design ideas examining epitaphs and tombstones using Google image search. Unfortunately, most of the models I found required 3D contouring. With that type of work, I would first need to spend the time creating a 3D model and even more hours carving it out.

There are three primary phases to a CNC project:

1) Design: The drawing or CAD model.
2) Tooling: Creating the tool paths with CAM software.
3) Machining: Running the tool paths on the machine.

I am admittedly an impatient man. With time being a finite resource we can never get back, isn’t everyone looking for a faster way? So, let me show you how you can use CNC routers to shortcut the 3D contouring process. First and foremost, you want to create your basic shapes and features using 2.5D operations. This is by far the biggest time saver. I’m talking about pocketing, profiling, and drilling mainly flat features on flat parts. You then follow it up with a bit of hand sculpting. This marriage between CNC and hand work produces impressive results for this type of project, while shaving valuable time from the process.

Figure 1. Cutting 2" foam stock

To start, I needed an inexpensive material that I could get from my local home improvement store that was easy to work with. The obvious choice was 2” thick foam insulation which I purchased in a 4 x 8 foot sheet for about $28. It’s thick enough to allow for a lot of depth and contrast in my design, which really pops when hit by a spot light on my lawn display. I happened to pick up a panel of pink Owens Corning — the one with the Pink Panther mascot (Figure 1). Other brands in other colors should work equally well.

I Think I CAM, I Think I CAM ...

My favorite piece of CAM software is Vectric’s VCarve Pro. This is by far the easiest-to-use CAM software on the planet. I also like how their software shows you a 3D preview of what the finished part will look like (Figure 2). I mention the CAM software first because the feature I like best is the built-in drawing tools, as opposed to other applications that require third-party drawing tools. This allows you to blend the first and second phases with a single piece of software.
 

Figure 2. 3D view of the  tombstoned esign in VCarve Pro.

Given that, we will skip the first phase and blend it in to the second phase when we get to that point.

This article is not intended to be a step-by-step tutorial, so I will not go into the details of how to use VCarve Pro. There are plenty of excellent tutorials and sample projects on their website if you need help using any of their software. You can download the design files for this project at the article link or at www.probotix.com/downloads to help get you started or if you want to simply recreate my design.

The first step in the CAM software is to define your stock (length, width, and height) and also where you want the origin (the zero location) to be. You can choose the back right corner at the bottom of the stock, top dead center, front left corner, or the top of the stock — it’s wherever you need it to be. It can depend on a lot of things, but typically people use the front left corner at the top of the stock.

The next step is to import your drawing from another drawing program. In this case, you can take advantage of Vcarve’s built-in drawing tools to create your shapes. I design machines and electronics for a living, so mechanical design comes naturally to me. However, I really struggle with organic design. So, whenever I come across a project like this, I rely on a variety of resources to help me.

Design, Fonts, and Clipart

There are plenty of sources of clipart available online, but many of them are click farms in disguise, so beware. I really like the CD-ROM/DVD clipart collections that include categorized catalogs (long live print!). Most of these designs require a lot of cleanup before they can be machined. They were not designed for CNC and will often have both disconnected and hidden vectors that have to be reworked first. Boolean drawing tools are your friend here.

Another great source of simple shapes are themed dingbat fonts. They require very little work to make them machinable. The horned head in my design was one of the “letters” in such a font. Speaking of fonts, there are tons of free font websites out there where you can find a multitude of themed type styles for your designs.

Once you are satisfied with your design, you will assign tool paths to the various shapes in it. Vcarve has a variety of tool path operations, but for this project we are only using the pocketing and profiling operations. With any of the tool path operations, you will be assigning the tool geometry, starting depth, depth of cut, step-over, feed rate, plunge rate, direction of cut, and so on. Because I was working with foam, I was able to take some overly aggressive cuts.

The order of operations is important when laying out your tool paths. For instance, you may need to cut your shallower pockets first when you have overlapping or embedded pockets. If the stock is being held from the outer edges, the last operation should be to do your final outside profile pass. I didn’t have an end mill long enough to make it through the whole slab of 2” foam, so on my outside profile, I cut it through as far as I could, then hand cut the rest of the way through with a knife. 

Now that you have your tool paths, you export them as g-code through the appropriate post-processor, and then carry that g-code over to the CNC machine on a USB thumb drive and load it into the control software. Our machines at Probotix run the open source software LinuxCNC.

Mount Up

I was cutting this particular part on the Probotix FireBall Comet™ CNC router that has a 25” x 25” work envelope (Figure 3). My foam slab was 18” x 24”, so I had to be careful that I mounted it to the table inside of the travel envelope of the machine. Double-sided 3M tape that has the green argyle backing is what I like to use for mounting stock to my table. Use a generous amount so the stock doesn’t come loose in the middle of the job.

Figure 3. Probotix Fireball Comet CNC Router. Figure 4. Screenshot of LinuxCNC showing tool paths.

Once the stock is mounted, install the tool into the spindle and then jog the tool over to the corner that you chose for the origin in the CAM software. Then, you will “touch off” each axis. What you are doing is telling the control software that you are now sitting at the starting point of each axis, or X0 Y0 Z0.

Give yourself a sanity check and look at the 3D toolpath on the display. You want to make sure that the tool path appears where you think it should within the work envelope bounding box on the screen (Figure 4). Then, hit the start button, sit back, and watch (Figure 5).

About 30 minutes later, you will have the basic tombstone carved out. So, pry it off the table and remove the double-sided tape. Figure 6 shows what it looked like after I cut off the outside scrap. Pretty cool already, but not very scary looking ... yet.

Figure 5. Fireball Comet in action - cutting the tombstone design. Figure 6. Tombstone after maching, but before handwork and paint.

The next step is to hand contour the piece to rough it up so it looks aged and weathered. There are many tools and methods you could use here, and you could spend a lot of time adding detail. Remember how impatient I am, though? I grabbed a die grinder with a rasp bit and a sanding wheel. I also used a hand rasp, and then smoothed out certain parts of the tombstone with some DAP fast drying latex caulk (Figure 7). Watch out for that die grinder — you can remove too much material in a hurry if you are not careful.

Figure 7. Die grinder, hand file, sand disc, and caulk.

Finishing Touches 

So far, so good, but have you ever seen a pink tombstone? Me neither. So, let’s change its color!

I love modern spray paint technology. There are many fast-drying exotic finishes available — your options are limitless. You can get a fantastic finish with little time and effort. A fleck stone spray paint finish was very tempting here, but since most spray paints will dissolve foam, I decided to use latex. I chose a satin gray as my base coat, and then used gray, black, and burnt umber mixes to weather and shade the tombstone (Figure 8).

Figure 8. Painting supplies and brushes.

Save Time, Save Money

You can spend a little time or a lot of time here. These tombstones are typically viewed under low light conditions, so I was looking mostly for contrast and depth, and that didn’t require a lot of time. Here is a breakdown of the time invested in this project:

  • Research: 3 hours
  • Design time: 1 hour
  • CNC routing: 30 minutes
  • Hand contouring: 10 minutes
  • Painting: 30 minutes

So, my total time was 5:10.

Compare that to the 10-20 hours that could easily be spent on a full CNC 3D contouring to accomplish the same thing (Figure 9)!

Figure 9. Finished tombstone decoration.


Ta-Da!

All-in-all, I was pretty satisfied with the results from such a small investment in time. If I were going to do this again, I would have spent more time and creativity on the tombstone verbiage. 

Do a Google search for “funny epitaphs” to get some inspiration. Maybe include names of family members or friends. Add an Arduino and LED lights. Then, make a whole graveyard full of them if you want! 

Most importantly, make sure to work safe and have fun! NV

 

Resources

Probotix Comet CNC Router
www.probotix.com

Royalty Free and Public Domain bitmap and vector clipart libraries
www.openclipart.org
www.pdclipart.org
www.clker.com

Files for this project
www.probotix.com/downloads

LinuxCNC
www.linuxcnc.org

Vectric Vcarve Pro
www.vectric.com

Free Fonts
www.dafont.com

Halloween Fonts
www.dafont.com/theme.php?cat=803

How to draw a creepy tombstone
www.fuelyourillustration.com/draw-acreepy-tombstone-using-adobe-illustrator/

Some definitions sourced from WikiPedia and other online resources


Posted on 10/14 at 2:41 pm
Posted in: Developing Perspectives

The Internet of Things

November 2014 Bryan Bergeron

Since the birth of the Internet, there has been talk of total connectivity — between people, people and their possessions, and things to things. Up until recently, the reality has been that such ecosystems existed only in academic and corporate research centers. Today, the Internet of Things (IoT) is a practical reality in many settings.


Let's start off with consumer goods. For the wellheeled, there's the Philips hue connected bulb ($60). It's a wireless bulb that screws into a regular light bulb socket. The difference is that you can control color and intensity via your iPhone or iPad from across the room or across the globe. If light bulbs aren't your thing (they don't do much for me), then another example of a commercially available IoT device is the Nest Protect smoke and carbon monoxide detector. No more surprises when you return from vacation to find all of your belongings smoldering from a house fire.

Then, there's the Parrot flower pot moisture sensor ($60) so that you know exactly when to water your roses, even when you're away from home. I haven't yet made the move to keyless locks. The Kwikset Kevo wireless deadbolt ($220) — while expensive enough to suggest it isn't a toy — leaves me a bit uncomfortable, knowing that a hacker could unlock my front door from his desk in some other country.

I'm partial to the web-enabled wireless cameras that can be accessed from anywhere. Check who's at the front door, keep an eye on the sitter, make sure the kids are doing their homework — the list is almost endless. Sure, this sort of snooping has been available for years, but never so "plug and play" with a smartphone.

On the non-commercial end of things, I've had the pleasure of working with some expensive gear that has yet to trickle down to the consumer market. My favorite is the pallet tracker. It's an RF unit that not only broadcasts the GPS location of the tagged pallet, but informs the receiver about handling and environmental conditions. 

For example, it can be set to sound an alarm if the internal accelerometer reads over 3 s, or, if the orientation of the tracker is shifted — as in flipped over. With such a device, it's possible to track a shipment across the globe, monitoring not only the location of the pallet but how it's been handled. (Be sure and check out the article this month by Ron Newton on a three-axis hockey puck accelerometer data logger that can be used for just such an application.)

I'm still waiting for a pair of running shoes that tell me not only how far and fast I've run — those have been available for years — but when it's time to buy a new pair of shoes based on impact sensors. It's the same with my toothbrush. I'm never certain exactly when to toss my brush for a new one. A connected brush that sends me an email after, say, 10,000 brushes would be helpful. I expect to see such a brush in my local CVS or Walgreens pharmacy within a year or two.

Best of all, I expect to see IoT kits that allow anyone to put anything on the Internet. Simply glue or nail it on whatever or whomever you want to track or control, and go about your business. One thing's for sure. With a mature IoT, I'll have to upgrade my data plan on my smartphone to avoid overuse charges. NV


Posted on 10/14 at 3:59 pm
Posted in: Nuts and Volts

New and in 3D: Automatic 3D data conversion and 3D-MID prototyping

October 2014

Aarbergen - At this year's Munich Electronica trade fair (November 11th-14th), Beta LAYOUT continues to announce interesting innovations. Brand new for Beta LAYOUT at Electronica is the introduction of “3D-MID prototypes.” Molded Interconnect Device (MID) is the production of moldings with integrated conductive structures. With "Brd - to - 3D,” Beta LAYOUT presents a comprehensive 3D package for its customers. The complete virtual circuit board package can be created directly from an EAGLE *.brd file. Features include photo realistic images of the PCB, SMD stencil, and STEP file generation.


3D-MID prototypes

Brand new for Beta LAYOUT at Electronica is the introduction of “3D-MID prototypes.” Molded Interconnect Device (MID) is the production of moldings with integrated conductive structures. In mass production, these moldings are manufactured using injection molding techniques. For prototyping purposes, this method is not economically feasible. Coming soon, Beta LAYOUT will offer the ability to manufacture MID components in prototype and small batch quantities, including the production of formed components by 3D printing, metallic coating, laser patterning, selective metallization, and mounting.

This technology is economically viable for engineers and companies with prototype and low volume quantity requirements. Start of production is planned for the second quarter of 2015. For design of 3D-MID components, developers can download the free PCB - POOL® edition of layout software TARGET 3001! which will have extended design features.

Brd-to-3D

With "Brd - to - 3D,” Beta LAYOUT presents a comprehensive 3D package for its customers. The complete virtual circuit board package can be created directly from an EAGLE *.brd file. Features include photo realistic images of the PCB, SMD stencil, and STEP file generation. In addition, a freely rotatable 3D view in PDF format is created which can be viewed using Adobe Reader. A link to order a laser sintered 3D model of the assembled PCB is provided, and a free 3D model is offered with PCB-POOL® prototype orders that can be used effectively for collision checking.

In addition, visitors to the Beta LAYOUT booth can receive information on the entire product range and services provided by Beta LAYOUT. These include PCB-POOL® - PCB prototype manufacture, PCB assembly, LASER STENCIL - SMD stencils, BETA – PROTOTYPES - 3D rapid prototyping, PANEL-POOL custom front plate manufacturing including color printing, and the BETA-eSTORE - tools and aids for prototype PCB assembly. www.beta-layout.com


Posted on 10/14 at 9:41 am
Posted in: Nuts and Volts

WiDo - Open Source IoT Node (Arduino Compatible)

October 2014

The WiDo Open Source IoT Node Arduino Compatible is a WIFI IoT Node development board, which integrates WG1300 WIFI solution. The Wido's microcontroller is ATMEL ATmega32U4 and is maker friendly. Fully compatible with Arduino and periphery modules. This is a credit card sized controller that comes with everything you need to connect to the cloud. And it's under $30! 


  • Arduino compatible WIFI IoT Node development board
  • Integrates WG1300 WIFI chip
  • Support 2.4GHz IEEE 802.11 b/g network
  • On board 2.4G PCB Antenna

 

Get yours today at the Robotshop.com


Posted on 10/14 at 9:14 am
Posted in: Nuts and Volts

Kickstarter: Dr.Duino

September 2014

Arduino has taken developers by storm, making developing your next widget easier than ever. But testing and debugging your next big thing is difficult and pains taking with Arduino. Stacked boards prevent access to the ones underneath it. Forcing you to stack and unstack your megalithic tower countless times each time bending pins out of shape, possibly breaking them. OUCH! What’s more, attaching probes for monitoring purposes is a pain, and what about a ground pin for my Oscilloscope, Digital Multi-meter (DMM) or Logic Analyzer?


Test Points, Test Points, Test Points!

Never struggle with where to grab a ground or monitor any signal from your Arduino to the shield above it again.

  • 4 large Gnd test points!!
  • 4 extra-large 5V &3 V test points.

Each test point is color coded for easy recognition.

  1. Green = Ground
  2. Red = 5 Volts
  3. Orange = 3.3Volts
  4. Black for Vref, Vin, and extra I/O!

RS-232 Baby!

Yep, built in RS-232 support out of box!

Communications Loop back testing supported by a simple jumper.

Built in Siren

Is your Arduino too far out of reach but need to know if an output is high or low? Well, assign your output pin to this little guy and BAM just listen for the siren! Better yet, this is connected directly to one of the PWM pins allowing you to control the volume.

Switch It UP

4 push button switches tied to input pins.

2 active high and 2 active low.

Light It UP

4 LED’s to help you debug your code.

Connected to the Arduino’s PWM pins allowing you to control brightness too!


POTs, POTs and more POTS

Six 10K large thumb wheel rotary Potentiometers pumped directly into the analog input pins.

Reset Switch

Reset your stack via the readily accessible reset switch.

How about some headers Please?

Every pin of the Arduino board has been brought out to a header. Allowing easy access for debugging purposes.

The window to your Boards Soul-

The middle of the Dr.Duino™has a hole! That’s right, simply plug your testy shield into any level of your stack. This allows you to still have access to all of your previous shields pins, IC’s, wires etc.

Pseudo Hardware

Were you struck in the middle of the night by your next invention but don’t have hardware on hand? Well, use the Dr.Duino™ kit and start writing your application code within mere milliseconds via commonly used hardware. Switches, POTS, LED’s, Sirens. Just plug in your Dr.Duino™ into your Arduino and start writing code!

 

Visit Dr. Duino Website to learn more! Or check out the Kickstarter to back the project! 


Posted on 09/14 at 2:57 pm
Posted in: Featured Article

The Ghost Phone

October 2014 Anthony Petrone

You walk into a darkened room where a rickety antique desk holds a dusty old telephone. To your surprise, it rings! You pick up the handset and hear static, hissing, and — just below the surface — the whispery words and scary sounds of a ghostly presence! You've just answered the Ghost Phone!


Figure 1A: Candlestick Style Phone

Since the days of old, many people believed the veil between the land of the living and the domain of the dead is at its thinnest on Samhain, All Hallows Eve, or — as we know it today — Halloween! Soothsayers, shaman, psychics, and mediums would all claim to provide patrons the privilege of speaking to their long-lost loved ones or would offer to carry back messages from the other realm — for a nominal fee, of course. So, how about we just skip the middleman and create a direct line to the afterlife? If this sounds like fun to you, then this fairly simple Halloween prop is just the ticket!

Propping It Up

I set out to create the Ghost Phone as a fun and interactive prop that anyone could make, using found objects and/or parts bought from local stores. Once the basic parts are gathered, it is unlikely that you'll spend more than a couple hours getting it all up and running since there's just a little wire splicing required. No tricky programming or custom-crafted printed circuit boards (PCBs) will be needed here. The premise is simple enough: When people get near the phone, it rings suddenly! Those brave enough to answer will be greeted with ghostly voices from the beyond.

There are three main components to this project; first of which is the phone itself. A suitable candidate can typically be found in a dusty corner of a thrift shop, in a box of junk at a garage sale, or maybe hidden in your very own attic. Second is the audio system which consists of a snap-action microswitch and a small MP3 player with a cheap set of headphones or earbuds. The third and final part is the ringer system. Though it may be possible to use the existing bells in the phone, I found it simpler to purchase an inexpensive low voltage electric bell and a "doorbell" style transformer to drive it. To control the ringer, I went to my local hardware store and purchased an off-the-shelf wireless light switching system that came with a handheld remote.

Though you can use pretty much any old corded phone for this project, I suggest you go for a style that fits the era of the haunted room in which you intend to use it. Victorian, Candlestick, WWII Army surplus, or even ‘50s era big black Bakelite style phones are all good candidates. Keep in mind that the modifications will likely render the phone unusable for "normal" phone service, so make sure you're not inadvertently destroying an expensive antique or family heirloom! For my haunt environment (classic Victorian haunt atmosphere), l found and purchased a replica Victorian-style phone.

Figure_1B: 50's Era Big Black Bakelite Style Phone Figure 2: Victorian Style Phone

Sounds ... Scary!

In operation, you want to give your guests the illusion that they are hearing voices from beyond the grave, but only when they pick up the receiver. To do this, I had to discover which wires went to the speaker in the earpiece of the phone handset. A quick search around Google and Wikipedia shows that many handsets used four wires: two for the microphone and two for the earpiece speaker.

Figure 3: Microphone to Speaker Wiring Schematic

We will need to access the two wires that go to the speaker in the handset. Lucky for us, older model telephones were long-lived devices and are typically easy to open for repairs. As such, it's normally a simple matter to unscrew the cover from the phone base and reveal the internal terminals and wiring. Once you have the cover removed, look carefully for the wires that come from the handset.

If you're lucky, they may be coded with the standard black/red/green/yellow colors. If this is so, you can try using the battery "tap test" to see if you can quickly identify the speaker. To do this, hold the green wire on the bottom terminal of the AA battery, then "tap" the red wire on the top terminal. At each tap, you should hear a pop and/or a slight crackle sound come from the speaker. If this doesn't make a sound on your first round, you can try each set of wires in turn until you hear the sound come from the ear piece.

If you prefer not to "experiment" looking for the speaker wires, you may disassemble the handset and check to see which two wires are connected to the earpiece. Many older phones feature a circular style ear and mouth piece on the handset that may simply be unscrewed. Some newer models may require you to pry the handset apart to gain access to the speaker.

Figure 4: Disassembled handset to find the speaker wire in the ear piece.

In any case, exercise caution not to break anything and make sure you can put it back together again. After you have identified which wires go to the earpiece in the handset, the next step is to modify the base.

Switch It Up

Once the speaker wires are located, we are going to wire in our MP3 player. We need an 1/8" stereo plug that ends in bare wires. If you have an old pair of ear buds or if your MP3 player came with a pair you are willing to sacrifice, simply cut the buds off the ends to create the cable we need. Carefully strip the wires from one side of the headphone cables (either the left or right speaker). Once you have stripped the wires, we are going to splice them into the handset speaker wires and our microswitch.

Figure 5: Wiring in the MP3 Player to the Phone.

In order to use the microswitch, we are going to find the "hook mechanism;" this is the piece that goes up and down when the handset is picked up. Depending on the type of phone you have chosen for this project, the next step might take some creativity. You will want to attach the microswitch to the moving piece of the hook mechanism so that when the phone is "on hook" (the handset is down), the connection to the speaker is open; when it's picked up ("off hook"), the connection is completed. I positioned my microswitch in such a way that the hook mechanism would push against it when the handset was down.

We want to wire one of the leads from our headset to the normally-closed position so that when the switch is released, the circuit is completed and the audio is allowed to play. Essentially, you will be breaking one side of the speaker connection with the microswitch.

You may need to remove most of the phone's internals to do this. That's okay, since we will want room inside to mount the MP3 player as well.

If you have followed these steps correctly, you should now be able to put a spooky MP3 of your choice onto the MP3 player and test out your work for the first part of this prop. Be sure to set your MP3 player to loop endlessly. Pick up the handset and make sure you can hear the player coming through the speaker.

If for any reason you cannot, be sure to check your wiring. These wires can often be very small and difficult to work with, so take your time and double-check your work. Be sure everything is working as it should, then reassemble the phone. If you picked a sufficiently small MP3 player, you should be able to hide it inside the phone itself. 

Figure 6: MP3 Player hidden in phone base.

There are plenty of great free spooky MP3 sounds you can download on the Internet, or you can make your own if you know how. Since we are using only one speaker, be sure to make your audio track of choice mono.

The second part of the prop allows the phone to ring when guests are near it and is much easier to make. To give the illusion of the phone's omnipresent sense for ringing, we are going to use an old-fashioned doorbell with a 2.5 inch bell and connect it to a wireless light outlet. The host can secretly hide the transmitter in their pocket or hand and control when the phone rings. These doorbells and the doorbell transformer can be found at most local hardware stores and online.

In order to hook the doorbell up to the wireless light outlet, we are going to use an old power cord for a PC and the doorbell transformer. The transformer will take the 120 VAC from the wireless light outlet and drop it down to a more usable 12-16 VAC for the doorbell itself.
 

Figure 7: The Doorbell Transformer hooked up to the Wireless Remote

Trim off the female end of the power cable and strip the wires back. Next, splice the end of the cable to the 120V side of the doorbell transformer and then wire the doorbell to the other side. Now, we can plug the cable into the outlet on the wireless transmitter, giving us a wireless ringer for the phone. You will need to turn the bell on and off by hand, so try to do so in a way that makes it sound like a phone ringing and not simply an endless ring.

Once the ringer is complete and tested, you can now hide it on the bottom of the table or desk that you are placing the phone on. Most tables and desks have a recessed area on the bottom which is perfect for hiding the mechanism. Practice a few times with the ringer to make sure you get the hang of making it sound like a phone, and be sure to stop once a guest picks up the handset! This prop is great because it has a nice startling effect of the loud bell ringing when people least expect it, and it's even creepier when guests realize they can answer the phone and hear the spooky voices from the other side.

This project was designed so that anyone could build it with simple-to-find parts, regardless of their skill level. A more advanced approach could be done using something such as an Arduino kit with an MP3 player board and PIR sensor to help automate the prop. You can find videos of the ghost phone in action at http://youtu.be/qx_Mujj_wbA.

For more fun Halloween project tips and ideas, be sure to check out my site at www.EerieAcresCemetery.comNV

 

 


Posted on 09/14 at 9:37 am
Posted in: Developing Perspectives

Don’t Get Stung by a Wall Wart

October 2014 Bryan Bergeron

Wall warts are used in place of internal AC-to-DC power supplies in most small devices — and for good reason. The powered unit can be more compact because of the obviously smaller parts count. There’s also no need to make allowances for convection cooling of components in the powered unit. The downside, of course, is the need to control a neverending, space-hungry herd of wall warts.


Until recently, a typical wall wart in my collection required at least two outlet spaces in my power strips: one for the prongs of the wall wart and at least one adjacent outlet partially obscured by the body of the wart. Given that new compact switching wall warts are so inexpensive, I recently upgraded my collection of conventional transformer and diode bridge warts to the switching variety. I’ve been happy with the upgrade — there’s more space in the outlets and less clutter around my workbench.

Unfortunately, I learned the hard way that the latest generation of “regulated output” switching wall warts can have at least one major shortcoming: the regulated output can be up to 100% over the stated output voltage with no load. For example, a 9 VDC wart can output up to 18 VDC with no load. This isn’t universal, but depends on the design of the switching supply.

I discovered this when I shipped out a dozen Arduino based animatronic systems for a research project. The systems left my shop — fully burned in — without a problem. However, the systems (which used 9 VDC switching wall warts for power) were DOA. I first thought of ESD, and modified the front end circuits of the animatronic systems to bleed off any electrostatic charges.

Luckily, before I sent the second batch of units off to the field, I ran across a thread in a forum about the no-load voltage levels in the same switching power supply warts I was using. It turned out that the users of my systems were plugging in the warts first, and then connecting the animatronic systems. This was guaranteed to generate a chipkilling spike if the no-load voltage was significantly greater than the load voltage. I solved the problem by ordering a dozen of the old-fashioned bulky wall warts with conventional non-switching circuitry. Problem solved — after quite a bit of expense repairing and reshipping the animatronic units.

Of course, not all switching wall warts suffer from this no-load voltage problem. The wall warts weren’t something I found on eBay. They were standard items from my favorite parts supplier. Bottom line: Verify that the wall wart’s output is what you expect before plugging it into that new system you’re designing. NV


Posted on 09/14 at 9:08 am
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